
ECSS‐E‐ST‐50‐14C
31July2008
24
5.2.1.2 Basic application scenario
Theinterfacespecifiedinthisclause5.2.1.2is definedonthe basisofatypical
analoguesignalmonitoringapplicationscenario,i.e.
• differentialvoltagerange:0to5Voroptionally0to5,12V;
• signalbandwidth:≤1Hz;
NOTE This means that accuracy requirements are
specified here assuming only slowly changing
(quasi‐static) signals. That does not prohibit, for
instance,rapidtransitionsin signals,but accuracy
isunspecifiedduring
suchevents.
• grounddisplacementvoltage:≤±1Vinthefrequencyrange0to1kHz,
fallingat20dBperdecadeupto1MHz;
• conversionresolution:12bits.
NOTE1 Thespecified12bitsresolutionisnotincompatible
with use of ADC having 14 or even 16 bits
resolution.Inthatcase,LSBareʺnotsignificantʺ.
NOTE2 Even if the overall channel accuracy requirement
in5.2.1.4canbemetalso with an8bitADC,itis
important to note that in this case the ADC
quantizationerrorcontributes±0,2%totheoverall
channelaccuracy,
thusnormallyagoodpracticeis
tousea12bitADC.
5.2.1.3 Applications other than the basic scenario
a. Iftheactualscenariodiffersfromtheonedefinedin5.2.1.2,theinterface
shallnotbedirectlyused.
NOTE1 Forexample,ifthespecificapplicationuseshigher
conversion accuracy or hasdifferent operational
conditions,e.g.higherdisplacement.
NOTE2 Inparticular,grounddisplacementheavilyaffects
the achievable conversion accuracy.
Different
scenario or specified performances can, for
instance,askforsourceimpedancebalancing.
b. The modifiedinterface shall be supportedby an analysis ofthe overall
system, including both interface source and receiver as well as
interconnectingwiring.
5.2.1.4 Acquisition of the analogue channels by the core
element
a. The errors introduced by the DHS receiver analogue acquisition chain,
including temperature, ground displacement voltage rejection, A/D
conversion inaccuracy, herein specified source impedance and cable
capacitance,supplyvoltagevariations,lifetimeandradiationeffectsshall
belessthan1%ofthefullscale.